A Shock to the System

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Regular shock-absorber replacement can help a trucking operator avoid getting a shock to the system. With the majority of trucks and trailers rolling off the production line equipped with air suspension, it is important to understand what regular shock-absorber replacement can do for your safety and your bottom line.

The main advantage of air suspensions is vastly improved load and equipment protection from vibration damage. As the load of the vehicle combination increases, the air pressure in the airbags is adjusted upwards to increase the spring rate of the vehicle, and is decreased as the load is removed.


An integral part of the air suspension is the shock absorber, which plays the crucial role of controlling the movement or oscillation of the air spring. The dampening of the shock absorber increases in line with the increased movement of the air spring, keeping the truck and trailer tyres in contact with the road surface, which has an overall affect on braking, control and vehicle stability.


At the end of the day, shock absorbers are a wearable item and will eventually need replacing, two key indicators are:


Tyre Wear


By far the biggest advantage of replacing worn out shock absorbers is a reduction in tyre wear, contributing one of the largest costs to a fleet or an owner-operator, behind fuel.


When the vehicle’s shock absorbers are worn out, the tyre will bounce in an uncontrolled manner, scuffing the road surface and leaving flat inconsistent wear spots on the tyre. This type of wear is also known as ‘scalloping’ due the appearance of the wear mark being similar to a potato scallop. This will significantly reduce the life of the tyre tread and casing due to impact damage.


It is worth noting if the tyre wear is more uniform on the outer or inner of the tyre, this is more of an alignment issue or a worn steering component.


Comfort and Control


Ultimately, worn-out shock absorbers will lead to a loss of vehicle control, allowing the air springs to oscillate more freely with less resistance from the shocks. Symptoms of this include increased time for the vehicle to settle after hitting a bump in the road, nose diving under brakes and floating sensations at high speeds. This type of vehicle behaviour can lead to driver fatigue due to the need for continual steering correction.


When should I replace my shocks?


Depending on the type of work the truck and trailer carries out, and the terrain it travels, shock absorbers should be replace at least every two years or even less in off-highway applications. Where the shock absorbers are fitted to trailers that carry fuel or in a stock-crate application, the shock absorbers work extremely hard providing load stability and should be included in a regular maintenance schedule.
When replacing shock absorbers, it is in your interests to choose a replacement unit that has been designed for Australia due to our unique climatic and road conditions. Many shock absorbers on the market today have been designed to operate in Europe or the US, in sub-zero temperatures, and will not last in our hot, dry conditions. Powerdown’s range of shock absorbers has been designed and developed in Australia, and the company has over 30 years of knowledge and experience operating in the country.